Disposable diaper

ABSTRACT

A disposable diaper comprises a rectangular absorbent pad which is longitudinally folded, at least at its crotch region, into a box-pleat configuration, and a flexible, moisture impervious backing sheet underlying the pad and being secured to the latter along the opposite marginal side portions of the pad, the backing sheet being longitudinally folded independently of the pad, at least at its crotch region, into a Z-shaped fold which underlies the central portion of the pad and which reduces the effective width of the backing sheet substantially to the same extent that the box-pleat configuration reduces the effective width of the pad.

United States Patent [191 [11; 3,731,688 Litt et al. 1 May 8, 1973 541 DISPOSABLE DIAPER 3,426,756 2/1969 Romanek ..128/237 [75] Inventors: Donald Litt, Scarsdale; David Jaroff,

New York; Amos Shamir, Riverdale, all of NY.

[73] Assignee: Techmation Corporation, Long Island City, NY.

[22] Filed: June 30, 1971 [21] Appl. No; 158,370

521 US. Cl. .....128/287 [51] Int. Cl. ..A6lf 13/16 [58] Field of Search ..128/286, 287

[56] References Cited UNITED STATES PATENTS 3,180,335 4/1965 Duncan et a]. ..128/287 3,295,526 1/1967 Sahee ..l28/287 Primary Examiner-Charles F. Rosenbaum Attorney-Lewis H. Eslinger et a1.

[57] ABSTRACT A disposable diaper comprises a rectangular absorbent pad which is longitudinally folded, at least at its crotch region, into a box-pleat configuration, and a flexible, moisture impervious backing sheet underlying the pad and being secured to the latter along the opposite marginal side portions of the pad, the backing sheet being longitudinally folded independently of the pad, at least at its crotch region, into a Z-shaped fold which underlies the central portion of the pad and which reduces the effective width of the backing sheet substantially to the same extent that the box-pleat configuration reduces the effective width of the pad.

11 Claims, 12 Drawing Figures PATENTEDHAY 8W 3,731,688

SHEET 2 [IF 3 F165. A FIGZ INVENTORS DONALD LITT DAVID JAROFF AMOS SHAMIR Z4 4ZAAL4 ATT-ORNEY PATENTEUHAY 8W5 3.731.688

SHEET 3 [1F 3 FIG. 12.

ATTORNEY DISPOSABLE DIAPER This invention relates to diapers, and more particularly is directed to improvements in disposable diapers that are intended to be discarded after a single use.

Disposable diapers are presently known in which a rectangular absorbent pad is composed of plies or layers of cellulose wadding covered by a porous, hydrophobic top sheet, and a similarly rectangular thin flexible back sheet of waterproof material extends over the outer surface of the absorbent pad and is secured to the latter along the margins of the pad. In order to provide such a diaper with an hour glass configuration for smoothly and comfortably fitting an infant when applied thereto, it has been proposed, for example, in US. Letters Pat. No. Re26,ll, issued Jan. 31, 1967, to jointly fold both the absorbent pad and the back sheet into a box-pleat configuration at least at the crotch region of the diaper. When applying the described disposable diaper, the opposite end portions are spread flat to provide sufiicient width for encircling the infants waist, while the box-pleat configuration is retained at the crotch region to provide a relatively large mass of absorbent material without undue bulk for avoiding discomfort to the infant.

However, it has been found that the folding of both the absorbent pad and back sheet jointly into the boxpleat configuration has the following disadvantages in use. At the crotch region of the diaper, folds of the waterproof back sheet are interposed between folds of the absorbent pad and constitute barriers to the rapid spread of moisture into the entire mass of absorbent material. Thus, the full capacity of the absorbent material for the rapid absorption of moisture cannot be utilized and there is the danger that, when moisture is discharged into the diaper at a high rate, some of the mositure will seep out of the diaper even though the total volume of such moisture does not exceed the capacity of the absorbent material for absorbing the same. Further, when the absorbent pad and water proof back sheet are jointly folded into the box-pleat configuration along the entire length of the diaper for simplifying the manufacturing and packaging of the described diaper, difficulties are experienced in holding the end portions of the diaper spread flat during the application of the diaper to an infant. Such difficulties result from the fact that the jointly folded pad and back sheet, after being spread flat at the end portions of the diaper, tend to resiliently return to the box-pleat configuration unless they are continuously held in the flattened conditron.

Further, in the disposable diaper of the above identified patent, the porous, hydrophobic top sheet which covers the plies of cellulose wadding has marginal side and end portions folded under and adhered continuously, as by uninterrupted stripes of adhesive,

to the underside of the assembly of plies. By reason of the foregoing, it is difficult to strip or separate the hydrophobic top sheet from the plies of cellulose wadding when the diaper is to be discarded and, therefore, users frequently flush the entire absorbent pad down a water closet with deleterious effects on the sewage system.

Accordingly, it is an object of this invention to provide a disposable diaper comprised of a generally rectangular absorbent pad and a similarly rectangular backing sheet of flexible, moisture impervious material, which diaper is afforded the desired hour glass shape for application to an infant while avoiding the above mentioned disadvantages of the described known diaper.

More particularly, it is an object of this invention to provide a disposable diaper, as aforesaid, in which the moisture impervious backing sheet does not interfere with the rapid spread of moisture throughout the full width of the absorbent pad, particularly in the crotch region therof.

Another object is to provide a disposable diaper, as aforesaid, which has a reduced tendency to resiliently return to its folded condition when the end portions of the diaper are spread flat preparatory to its application to an infant.

A further object is to provide a disposable diaper, as aforesaid, in which separation or stripping of the porous, hydrophobic top sheet from the layers of cellulose wadding included in the absorbent pad is facilitated, whereby to ensure that only the cellulosic wadding will be flushed into sewage systems to protect the latter from clogging or other damage.

In accordance with an aspect of this invention, only the absorbent pad of the disposable diaper is longitudinally folded, at least at its crotch region, into a boxpleat configuration, and the flexible, moisture impervious backing sheet is longitudinally folded independently of the pad, at least at its crotch region, to provide a Z-shaped fold therein which underlies the central portion of the absorbent pad and which reduces the effective width of the backing sheet substantially to the same extent that the box-pleat configuration reduces the effective width of the pad.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment of the invention which is to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a plan view of an absorbent pad included in a disposable diaper according to this invention, and which is shown with a top sheet thereof partly broken away;

FIG. 2 is a plan view of the absorbent pad following the folding thereof into a box-pleat configuration;

FIG. 3 is an end view of the absorbent pad in its folded condition;

FIG. 4 is a plan view of a backing sheet also included in the disposable diaper according to this invention;

FIG. 5 is a plan view of the backing sheet following the folding thereof to provide a Z-shaped fold therein;

FIG. 6 is an end view of the backing sheet in its folded condition;

FIG. 7 is a plan view showing the folded absorbent pad superposed on the folded backing sheet;

FIG. 8 is a plan view of the completed disposable diaper according to this invention, and which is shown in the condition thereof for convenient packaging;

FIG. 9 is an enlarged, transverse sectional view of the disposable diaper taken along the line 9-9 on FIG. 8;

FIG. 10 is a plan view similar to that of FIG. 8, but showing the disposable diaper with its end portions spread flat preparatory to the application of the diaper to an infant;

FIG. 11 is a fragmentary, enlarged sectional view taken along the line l1-1 1 on FIG. 10; and

FIG. 12 is a plan view similar to that of FIG. 10, but showing the outer face of the diaper which is to be directed away from the body of an infant to which the diaper is applied.

Referring to the drawings in detail, it will be seen that a disposable diaper (FIGS. 8-12) according to this invention generally comprises a rectangular absorbent pad 11 (FIG. 1) hereinafter described in detail, and a rectangular backing sheet 12 (FIG. 4) of a thin, flexible, moisture-impervious material, such as, polyethylene or the like, having a length and width greater than the corresponding dimensions of absorbent pad 11. For example, in a typical disposable diaper according to this invention, absorbent pad 11 has a length L of 16 inches and a width W of approximately 13 inches, whereas the backing sheet 12 has a length L of approximately 18 inches and a width W of approximately inches.

The absorbent pad 11, as particularly shown on FIGS. 9 and 11, may be composed of a number of superposed sheets or layers of creped cellulose wadding 13 which is highly moisture absorbent, and a porous hydrophobic sheet 14, for example, of a non-woven rayon fabric containing a suitable resin binder. As shown particularly on FIGS. 1 and 11, the sheets 13 of cellulose wadding and the porous, hydrophobic top sheet 14 may be coextensive in their longitudinal directions, whereas the top sheet 14 is wider than the sheets 13 of wadding so as to provide side flaps 15 which are to be folded under the opposite marginal side portions of the stack of sheets 13 and secured to the lowermost sheet 13, as by joint embossing or by stripes of a suitable adhesive, such as, a micro-crystalline wax hot melt available commercially from National Starch & Chemical Corporation under the designation Instalock hot melt resin No. 342933. The opposite end edge portions of the porous, hydrophobic top sheet 14 are further secured to the sheets of cellulose wadding 13, for example, as by joint embossing or the previously mentioned hot melt, only at laterally spaced apart locations, for example, at the areas indicated in broken lines at 16 on FIG. 1, for a purpose hereinafter indicated in detail. The sheets of cellulose wadding 13 are preferably arranged with the ridges of the creping thereof, indicated at 17 on FIG. 1, extending transversely with respect to the longitudinal direction of pad 11 for a purpose that is also hereinafter described in detail.

The opposite side portions of pad 11 are folded upwardly and inwardly relative to the central portion 18 about longitudinal fold lines 19 and 20 (FIG. 1) which are laterally spaced apart by a distance, for example, 4% inches, approximately equal to the desired width of the completed diaper 10 at the crotch region thereof.

Further, the side portions of pad 11 are folded out-.

wardly about longitudinal fold lines 21 and 22 (FIG. 1) which are respectively approximately midway between fold lines 19 and 20 and the adjacent side edges or margins of pad 11. Thus, pad 1 1 is folded so as to have two longitudinal Z-shaped folds 23 and 24 in its opposite side portions which are directed toward each other over central portion 18 to provide the pad with a boxpleat configuration (FIGS. 3 and 9) opening centrally in the upward direction, that is, along the face of the diaper to be contacted with the infant's body. The Z- shaped folds 23 and 24 of pad 11 are preferably laterally dimensioned with respect to the width of central portion 18 so that the inner or confronting edges of folds 23 and 24 will be spaced apart, as at 25 on FIG. 2, for example, by a distance of approximately onequarter to one-half inch, while the free side edges or margins 26 and 27 of the folded pad 11 are approximattly aligned with the fold lines 19 and 20 which define the opposite side margins of central portion 18 (FIG. 3).

The absorbent pad 11, as described above, may have all of the operations necessary for its manufacture performed while the various materials included in the pad are moved longitudinally in a single direction. Thus, for example, the creped cellulose wadding 13, as received in roll form from the manufacturer thereof, has the ridges 17 of its creping extending axially on the roll, that is, extending transversely with respect to the continuous web which is unwound from the roll and, while being moved longitudinally, may be cut along longitudinally spaced apart, laterally extending cut lines to provide the sheets 13 of the desired dimensions. Such cut sheets 13 are further moved longitudinally and stacked one upon the other, whereupon the porous, hydrophobic top sheet 14, which may also be cut from a continuous unrolled web, is moved longitudinally and disposed upon the stack of sheets of cellulose wadding 13. The hot melt or other adhesive for securing sheet 14 to the stack of sheets 13 may be suitably applied to sheet 14 at the spaced apart areas 16 and along the opposite marginal side portions 15 during the longitudinal movement of sheet 14 onto the stack of sheets 13. After sheet 14 has been disposed on the stack of sheets 13, the sheets 13 and 14 are moved longitudinally as a unit and the opposite marginal side portions 15 of sheet 14 are folded under and adhered to the corresponding marginal side portions of the lowermost sheet 13 in the stack thereof to complete the pad and, during further longitudinal movement of completed pad 11, the latter may be longiduinally folded into the described boxpleat configuration. Prior to such longitudinal folding of pad 11 into the box-pleat configuration, adhesive, for example, the above described hot melt, may be applied to limited areas 29 (FIG. 1) of the top surface of the pad which are located between fold lines 19 and 21 and fold lines 20 and 22, respectively, approximately midway between the opposite ends of the pad. The adhesive at limited areas 29 thereafter serves to secure the Z-shapecl folds 23 and 24 and thereby retain pad 11 in its box-pleat configuration only at the crotch region of pad 11.

During the production of each pad 11, as described above, a corresponding backing sheet 12 may be produced while moving longitudinally along a production line disposed under the production line for the pad 11. In thus producing each backing sheet 12, the latter is suitably cut from a web of the corresponding material being unwound longitudinally from a roll thereof and, during longitudinal movement of sheet 12, the opposite side portions of the sheet are folded in opposite directions about two laterally spaced longitudinal fold lines 30 and 31 (FIG. 4) so as to extend over and under, respectively, the central portion 32 of sheet 12 defined between fold lines 30 and 31, as particularly shown on FIG. 6. Thus, a single Z-shaped fold 33 (FIG.6) is formed longitudinally in backing sheet 12, and the distance between fold lines 30 and 31 is selected to be less than one-third the overall width W of backing sheet 12 so that, when in its folded condition (FIG. 6), the opposite marginal side portions 34 and 35 of sheet 12 will project laterally beyond fold lines 30 and 31. More particularly, the distance between fold lines 30 and 31 is selected so that the difference between the initial width W of sheet 12 and the effective width w of that sheet in its folded condition (FIG. 5) will be substantially equal to the difference between the initial width W of absorbent pad 11 and the effective width w (FIG. 2) of the absorbent pad in its folded condition, that is, so that the single Z-shaped fold 23 in backing sheet 12 reduces the effective width of the latter to the same extent that the effective width of absorbent pad 1 1 is reduced by the two Z-shaped folds 23 and 24 provided therein to form the box-pleat configuration.

Prior to the folding of backing sheet 12, a suitable adhesive, for example, the above mentioned hot melt, is appleid to a limited area 28 (FIG. 4) located between fold lines 30 and 31 approximately midway between the ends of sheet 12. Thus, when sheet 12 is folded, as described, the adhesive at area 28 serves to secure the Z-shaped fold 33 at the crotch region.

The folded pad 11 is disposed on top of the folded backing sheet 12, for example, by longitudinal movement of the folded pad onto the folded backing sheet, so that Z-shaped fold 33 of the backing sheet will underlie the central portion 18 of folded pad 11 and the opposite marginal side portions 34 and 35 of the backing sheet will extend laterally outward with respect to the side edges of the folded pad (FIG. 7). Then, for example, during longitudinal movement of pad 11 and backing sheet 12 as a unit, stripes 36 and 37 of a suitable adhesive, for example, the above mentioned hot melt, are applied to the upwardly facing surfaces of marginal side portions 34 and 35 and the latter are folded upwardly and inwardly for example, about the fold lines 38 and 39 indicated on FIG. 4, so as to overlie, and be adhered to the adjacent marginal side portions of pad 11 (FIGS. 8 and 9).

The thus completed disposable diaper is relatively flat and has a substantially long and narrow rectangular configuration (FIG. 8) for convenient packaging.

When disposable diaper 10 is to be applied to an infant, the diaper is placed on a suitable supporting surface with opening of the box-pleat configuration of pad 11 facing upwardly, and the two end portions of the diaper are opened or spread flat so as to give an hour glass shape to the diaper, as shwown on FIG. 10. In thus spreading flat the end portions of diaper 10, the two Z-shaped folds 23 and 24 of pad 11 and the single Z-shaped fold 33 of backing sheet 12 are separately opened in a progressive manner from the crotch region, where the folds are adhesively secured, towards the ends of the diaper, as shown on FIGS. 10 and 12. Since the folds 23 and 24 of the absorbent pad and the fold 33 of the backing sheet are formed independently of each other and not interleaved with each other, the resilient tendencies of such folds to return to their folded conditions are not mutually reinforcing. Therefore, the end portions of diaper 10, when opened or spread flat, as described, have a relatively reduced tendency to return to the folded condition of FIG. 8, as compared with the disposable diaper disclosed in the previously mentioned patent No. Re. 26,151, wherein the pad and backing sheet are jointly folded together into the box-pleat configuration. After the end portions of diaper 10 have been spread flat, the diaper is applied to the infant in the usual manner, that is, the corners at opposite sides of the front end portion of the diaper are secured to the corresponding comers at the back end portion of the diaper so that the end edges of the diaper encircle the infants waist and the arcuate edges appean'ng at the opposite sides of the diaper on FIG. 10 define the leg openings of the applied diaper.

With the diaper thus applied, the middle portion of the diaper, where the Z-shaped folds 23 and 24 of the pad and the single Z-shaped fold 33 of the backing sheet are secured or held closed, forms the crotch region. At such crotch region, a relatively large mass of absorbent pad 1 l is provided, without undue bulk so as to provide a large moisture absorbing capacity. Further, in the diaper embodying this invention, as particularly shown on FIG. 9, the folding of moisture-impervious backing sheet 12 independently of absorbent pad 11 ensures that the moisture-impervious material of backing sheet 12 is not disposed between folds of the absorbent pad 11, particularly at the crotch region of the diaper. Thus, moisture entering the crotch region of the applied diaper is free to spread throughout the folds 23 and 24 and into the central portion 18 of the absorbent pad and the backing sheet 12 does not constitute a barrier to the rapid spread of moisture throughout the absorbent pad. This is to be distinguished from the situation in the diaper disclosed in the previously mentioned US. Pat. No. Re26,l5l, in which folds of the moisture-impervious backing sheet are interposed between, or interleaved with folds of the absorbent pad at the crotch region and thereby constitute barriers to the rapid spread of moisture throughout the absorbent pad.

Following removal of the used diaper from an infant, any solid waste matter may be rinsed from the diaper, as in a water closet, and then the backing sheet 12 is stripped from the absorbent pad 11 and separately disposed of, as in a suitable waste container. The top sheet 14 and sheets or layers of cellulose wadding 13 are then independently grapsed at one end of the remaining absorbent pad 11. Such separate grasping of the sheets 13 and 14 is facilitated by the fact that the ends of such sheets are secured to each other only at the spaced apart areas 16. The independently grasped sheet 14 is then stripped from the sheets or layers 13 and preferably separately disposed of in the waste container. Finally, preferably only the sheets of cellulose wadding 13 are disposed of by flushing in the water closet. Thus, only the easily dispersed cellulose wadding is conveniently flushed into the sewage system so as to avoid any damage to the latter.

Although an illustrative embodiment of this invention has been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.

What is claimed is:

1. A disposable diaper comprising a generally rectangular absorbent pad having two longitudinal Z-shaped folds in its opposite side portions which are directed tacted with the wearers body, a generally rectangularbacking sheet of flexible, moisture-impervious material that is at least wider than said pad and has a single longitudinal Z-shaped fold in its central portion reducing the effective width of said backing sheet substantially to the same extent that the effective width of said absorbent pad is reduced by said two Z-shaped folds of the latter, said Z-shaped fold of the backing sheet underlying said central portion of the pad at the surface of the latter which faces away from the opening of said box-pleat configuration, and marginal portions of said backing sheet, at the opposite sides of the latter, being folded over and adhered to corresponding marginal side portions of said pad.

2. A disposable diaper according to claim 1, further comprising means holding closed said Z-shaped folds in the pad and backing sheet only at locations that are approximately midway between the opposite ends of said pad and backing sheet.

3. A disposable diaper according to claim 1, in which said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is substantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spacedv apart locations along the opposite end edges thereof.

4. A disposable diaper according to claim 3, in which said layers of the absorbent pad are creped with the ridges of the creping thereof extending substantially in the direction of the width of said pad.

5. A disposable diaper according to claim 1, in which said backing sheet is also longer than said absorbent pad and substantially free of the latter along its opposite end edges.

6. A disposable diaper comprising a generally rectangular absorbent pad and a generally rectangular backing sheet of flexible, moisture-impervious material underlying said pad and being at least wider than said pad, the opposite marginal side portions of said backing sheet being folded over and adhered to the adjacent marginal side portions of said pad, said pad being folded about four spaced apart longitudinal fold lines into a box-pleat configuration opening centrally along said pad in the direction away from said backing sheet, and said backing sheet being folded independently of said pad about two spaced apart longitudinal fold lines into a Z-shaped fold which underlies the central portion of said pad, the difference between the widths of said backing sheet in its flat condition and with said Z- shaped fold, respectively, being approximately equal to the difference between the widths of said pad in its flat condition and in said box-pleat configuration, respectively.

7. A disposable diaper according to claim 6, further comprising means holding closed said Z-shaped fold and holding said pad in said box-pleat configuration only at locations approximately midway between the opgositeends of said backing sheet and ad.

A disposable diaper according to c aim 6, in which.

said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is sub stantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spaced apart locations along the opposite end edges thereof.

9. A disposable diaper comprising a generally rectangular absorbent pad and a rectangular backing sheet of flexible, moisture-impervious material underlying said pad and being secured to the latter at least along the opposite marginal side portions of the pad, at least the crotch region of said pad being folded about four spaced apart longitudinally directed fold lines into a box-pleat configuration opening centrally in the direction away from said backing sheet, and at least the crotch region of said backing sheet being folded independently of said pad about two spaced apart longitudinally directed fold lines into a Z-shaped 'fold which underlies the central portion of said pad, the extent to which said Z-shaped fold reduces the effective width of said backing sheet being approximately equal to the extent by which the effective width of said pad is reduced by said box-pleat configuration.

10. A disposable diaper according to claim 9, further comprising means holding said backing sheet folded in said Z-shaped fold and means holding said pad folded in said box-pleat configuration only at said crotch regions of said backing sheet and pad, respectively.

11. A disposable diaper according to claim 9, in which said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is substantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spaced apart locations along the opposite end edges thereof. 

1. A disposable diaper comprising a generally rectangular absorbent pad having two longitudinal Z-shaped folds in its opposite side portions which are directed toward each other over a central portion of the pad to provide the latter with a boxpleat configuration opening centrally along the face of the diaper to be contacted with the wearer''s body, a generally rectangular backing sheet of flexible, moisture-impervious material that is at least wider than said pad and has a single longitudinal Z-shaped fold in its central portion reducing the effective width of said backing sheet substantially to the same extent that the effective width of said absorbent pad is reduced by said two Z-shaped folds of the latter, said Z-shaped fold of the backing sheet underlying said central portion of the pad at the surface of the latter which faces away from the opening of said box-pleat configuration, and marginal portions of said backing sheet, at the opposite sides of the latter, being folded over and adhered to corresponding marginal side portions of said pad.
 2. A disposable diaper according to claim 1, further comprising means holding closed said Z-shaped folds in the pad and backing sheet only at locations that are approximately midway between the opposite ends of said pad and backing sheet.
 3. A disposable diaper according to claim 1, in which said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is substantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spaced apart locations along the opposite end edges thereof.
 4. A disposable diaper according to claim 3, in which said layers of the absorbent pad are creped with the ridges of the creping thereof extending substantially in the direction of the width of said pad.
 5. A disposable diaper according to claim 1, in which said backing sheet is also longer than said absorbent pad and substantially free of the latter along its opposite end edges.
 6. A disposable diaper comprising a generally rectangular absorbent pad and a generally rectangular backing sheet of Flexible, moisture-impervious material underlying said pad and being at least wider than said pad, the opposite marginal side portions of said backing sheet being folded over and adhered to the adjacent marginal side portions of said pad, said pad being folded about four spaced apart longitudinal fold lines into a box-pleat configuration opening centrally along said pad in the direction away from said backing sheet, and said backing sheet being folded independently of said pad about two spaced apart longitudinal fold lines into a Z-shaped fold which underlies the central portion of said pad, the difference between the widths of said backing sheet in its flat condition and with said Z-shaped fold, respectively, being approximately equal to the difference between the widths of said pad in its flat condition and in said box-pleat configuration, respectively.
 7. A disposable diaper according to claim 6, further comprising means holding closed said Z-shaped fold and holding said pad in said box-pleat configuration only at locations approximately midway between the opposite ends of said backing sheet and pad.
 8. A disposable diaper according to claim 6, in which said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is substantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spaced apart locations along the opposite end edges thereof.
 9. A disposable diaper comprising a generally rectangular absorbent pad and a rectangular backing sheet of flexible, moisture-impervious material underlying said pad and being secured to the latter at least along the opposite marginal side portions of the pad, at least the crotch region of said pad being folded about four spaced apart longitudinally directed fold lines into a box-pleat configuration opening centrally in the direction away from said backing sheet, and at least the crotch region of said backing sheet being folded independently of said pad about two spaced apart longitudinally directed fold lines into a Z-shaped fold which underlies the central portion of said pad, the extent to which said Z-shaped fold reduces the effective width of said backing sheet being approximately equal to the extent by which the effective width of said pad is reduced by said box-pleat configuration.
 10. A disposable diaper according to claim 9, further comprising means holding said backing sheet folded in said Z-shaped fold and means holding said pad folded in said box-pleat configuration only at said crotch regions of said backing sheet and pad, respectively.
 11. A disposable diaper according to claim 9, in which said pad includes a plurality of layers of cellulose wadding and a porous hydrophobic sheet which is substantially coextensive with said layers in the direction of the length of said pad and wider than said pad, said porous hydrophobic sheet overlying said layers and having its opposite marginal side portions folded under and adhered to the adjacent marginal side portions of said layers, and means further adhering said porous hydrophobic sheet to said layers only at laterally spaced apart locations along the opposite end edges thereof. 